Mercury vapor rectifier



fi 1931' M. A. E. LEBLANC 1,839,154

MERCURY VAPOR RECTIFIER Filed Aug. 15, 1927 lnven c01 MaL.u-ice A. E.LeBlanc,

byMM/M His Attorneg.

" with the constructional form of the movable Patented Dec. 29, 1931 vuNrrEosrA Esf rArsN'r OFFICE Manama aueusra zuemm anuxc, or suaasrus,FRANCE, assmuoa, BY 1mm assrommm's, 'ro 91mm morale comm, a CORPORATIONor mm YORK Application filed A'lllultli, 1827, Serial" Io.-

This invention relates to mercur vapor rectifyingand the like apparatusan has for its main object to provide improved arrangements for startingor li htiug up apparatus of this character in whic a movable starting orlighting up electrode device is employed,

In order to start or light up mercury vapor rectifying apparatus, forexample, a mov-' able electrode mounted at the extremity of a bimetallicelement has been employed, the bi-' metallic element being arranged tobe deformed when heated in any suitable manner so as to move theelectrode out of, the mercury cathode of the apparatus, inzwhi'ch it, isimmersed when at rest, and thereby start or light up the apparatus uponbreaking contact between the mercury cathode and movable electrode, itbeing understood that a current is caused to flow between the cathodeand movable electrode when it is required to start the apparatus.

The present invention is applicable essentially to this particularsystem of starting or lighting up and is concerned more especiallyelectrode device and with the protection of the latter against variouscauses of deteri0-. ration on the one hand, and on the other hand. withvarious electrical circuit arrangements permitting he employment of theimproved movable electrode device. r a

As regards the practical constructional form of the movable electrodedevice the bimetallic portion thereof is protected against directcontact with ionized vapor, soas to avoid all risk of deterioration thisbeing at-- tained, for example, by meansof a screen or.

tungsten, which is not volatilizedunderflthe screens of insulatingmaterial and'the electrode portion itself, which. is arranged to'beimmersed in the mercury cathode when at rest, consists of material, suchforexample as auxiliary electrical 'systems, casings or lmncunx varoa213,15 mi ln'irance s uam- :1, me.

I electrode device a .deviceis employed for preventing the flow ofcontinuous current in the circuit of the starting or lighting upelectrode device, in the event of the starting or lighting up arc beingproduced with the movable electrode. device as the cathode, on the onehand and on the other hand for placing the 'whole. of the movable,electrode at the same potential as the cathode when once the main ar chas been struck. This result can be attamed, either by employing asuitable relay for breaking the starting or' excitation circuit when theapparatus is started or lit up and consequently preventing the flow ofcontinuous current which would tend to-be established in the starting orexcitation circuit, or by inserting in this circuit a condenser alone ora condenser accompanied by an induction coil.- In the case where a relayis employed in'the starting or excitation circuit of apparatus ofrelatively great power a device isemployed for starting at low load andpermltting the closing of the output circuit of the apparatus only whenthe main arc is struck. c The devices utilized for thepurposessmentioned above may be constituted either by circuit breakingor, the like devices, or by g mgs provided'onthe exterior or in theInterior of the projecting "anode arms of theapp'aratus, these devicesbeing controlled by systems of'suitablerelays in such manner as toprevent starting under load.

Inorder that the invention may be clearly,

understood it will'now be described by way of example, with reference tothe accompanying drawings, in which Figure 1 ,is va view of an improvedco nstru'ctional form of movable starting orlighting up electrode deviceapplied to mercury vapor rectifying apparatus.

- Figure 2 is a diagrammatic view of improved circuitiarrangem'ents forstarting rectifying apparatus for relatively smallcure rentsatrelatively low pressure.

Figure 3 is'a diagrammatic view of modi- 'fied circuit arrangementssuitable for rectifying apparatusof comparatively great capacity andprovided with a maintaining circuit through a permanent shunt.

Figure 4 is a diagrammatic view of further modified circuit arrangementssuitable for rectifying apparatus of comparatively great capacity andprovided with a maintaming circuit through special electrodes, and

igure 5 is a view of a rectifying apparatus provided with a starting orexcltation clrcuit having a condenser therein.

Referring first to Figure 1, the lead 1 for the starting or excitationcurrent is mounted in a prO ecting portion of the lateral wall of themercury vapor rectifying apparatus, and is connected at 2 to oneextremity of a bimetallic element 3 which is connected at its otherextremity 4 to a tungsten starting electrode 5 covered with glass for aconsiderable portion of its length intermediate its extremities asillustrated. The lower uncovered portion 6 of the bimetallic element 3is normally in contact with the mercury in the apparatus and it is thebreaking of this contact which effects the striking of an are forstarting or lighting up the apparatus. The whole of the bimetallicelement to ther with its :onnections with the lead 1 an electrode 5 isprotected from direct contact with the ionized vapor by an insulatingtube 7, of glass for example, the lower extremity of WhlCh is supportedby a flange 8 provided on the covering of the electrode 5. It will beevident that, if a current sufiicient for heating the element 3 iscaused to flow in a circuit including the starting electrode 5 and thecathode of the apparatus, the element 3 will be deformed and the circuitwill be broken down between the portion 6 and the mercury, thus strikingan are for starting or lighting up the apparatus, it being understoodthat the play of the electrode 5 and insulating tube 7 as a whole isarranged to be sufficient to permit the deformation of the element 3 tothe required extent. The general elevation of the temperature of therectifying apparatus during operation also causes the element 3 to beheated and deformed so that the electrode 5 is raised but thisdeformation is not of importance. It is however, of advantage to adjustthe element 3 so that when the rectifying apparatus is operating at arelatively small difference of potential, that is to say at a relativelylow temperature, the portion 6 of the electrode 5 is just at the surfaceof the mercury, thus permitting the cathode glow to be fixed on thesurface of the mercury and increase the stability of the main arc.

Before describing various electrical circuit arrangements (Figures 2 to5) for use in connection with the bimetallic starting element, it shouldbe observed that the starting or lighting up of the rectifymg apparatusis effected by breaking contact between the mercury and the electrode 5and thus cutting off the current heating the bimetallic element, thiscurrent usually being alternating in character as the employment ofcontinuous current for this purpose introduces complications. Contact istherefore broken sometimes with the mercury and sometimes with theelectrode 5 as the cathode, and the circuit arrangements utilized shouldtherefore be capable of selecting between these two cases, and main arcof the rectifying apparatus should only be able to be struck when thecathode glow is on the mercury. Moreover experience has shown that whenthe main arc 'of the rectifying apparatus has been struck the startingelectrode 3 should be placed at the same potential as the cathode, if itis desired to avoid all danger of striking a cathode glow on themetallic portions of the starting electrode.

Circuit arrangements for use with rectifying apparatus for smallcurrents at low pressure are illustrated in Fi ure 2 and referring nowto this figure it will e observed that the anodes 10 of a mercur vaporlamp 9 are arranged to be energized by an autotransformer 11 which isitself energized through the leads 12. A winding 13 is provided on thecore of the autotransformer 11, this winding being connected on one handto the cathode 14 of the lamp and on the other hand to a bimetallicstarting electrode device 15 through the two contacts 16 of a relay andthrougha resistance 17. The cathode 14 of the lamp 9 is moreoverconnected to a self inductance 18 arranged in series with the winding 19of the relay. When the mercury vapor lamp is not operating and theautotransformer 11 is energized, alternating current is supplied to thecircuit 13, 14, 15, 16, 17 and the bimetallic starting electrode device15 is heated, thus causing contact between the electrode 15 and themercury to be broken.

When the mercury is the cathode at the moment of breaking contact, andif the phase is favorable, the ,lamp 9 is started normally continuouscurrent being supplied to the winding 19 of the relay with the resultthat the two contacts 16 are opened so as to cutoff the starting orlighting up current and permit the bimetallic starting electrode device15 to assume the same potential as the cathode. The bimetallic startingelectrode device 15 cools and comes into contact with the mercury andfixes the cathode glow. If on the contrary the phase is unfavorable, thebimetallic starting electrode 15 becomes cold, and comes into contactwith the mercury, and the starting or excitation circuit being yetclosed new break of contact is effected.

When however the electrode 15 is the oathode at the moment of breakingcontact and if the phase is favorable, continuous current is supplied tothe circuit 15, 17, 16, 13, 18, 19 but is cut off at the two contacts16, which are closed at once, and the same process continues to becarried out until normal starting is eflected.

It will be observed that the relay 16, 19 effects the selection betweenthe normal and reverse starting or lighting up and on the other handplaces the electrode 15 at the same potential as the cathode when normalstarting is effected.

It is to be observed that the contacts 16 of the relay shouldbe on theone hand capable of cutting off all the continuous current load on theone hand and on the other hand of offering a resistance to the passageof current which is sufliciently small so as not to limit the startingor excitation current even if a winding 13 of very low pressure isemployed.

It has been assumed until now that the relay 16, 19 and self inductance18, are separate from one another but they could be constructed as asingle device by utilizing the flux due to self inductance 18 to movethe contacts 16 which may be of any desired form.

The circuit arrangement illustrated in Figure 2 which is applicable torectifying apparatus for small currents at low pressure fails in thecase of rectifying apparatus of comparatively great capacity. In fact,if it were used in the latter case without modification, and the cathodeglow were formed on the starting electrode 15 when starting, the totalcurrent supplied by the rectifying apparatus would be liable to flowthrough the starting electrode 15 and this current would have to be cutoil by the contacts 16, wherebv rapid deterioration of both the contacts16 and electrode 15 would be caused.

It is therefore necessary, in the case of apparatus of comparativelygreat capacity, to effect the striking of the arc of comparatively smalldifl'erence of potential through an auxiliary circuit, and to permit theclosure of the continuous current circuit only after having normallyobtained the striking of the arc.

In Figures 3 and 4 two circuit arrangements of this character areillustrated as applied to rectifying apparatus provided with amaintaining circuit through a permanent shunt (Figure 3) and on theother hand to rectifying apparatus provided with maintaining electrodes.

In Figure 3, the autotransformer 20, which is illustrated as a monophasetransformer, is arranged to energize the two anodes of the mercury vaporlamp 21. A winding 22 is provided on the core of the tran'sformer 20 forenergizing the cathode and starting electrode circuit through aresistance 23 and a relay provided with two opening contacts 24.

A resistance 25, serving as a shunt for maintaining the main arc, isconnected across the apparatus and is arranged in series with a winding26 provided for actuating the contacts 24.

In the output circuit of the rectifying apparatus a circuit breakingdevice 27 is inserted which is adapted to beactuated upon the passage ofalternating current at a difference of potential equal to the differenceof pressure between the anodes and the neutral point of the transformer20. The actuating circuit of the circuit breaking device 27 may beclosed either by the contacts 28 of a maximum current relay arranged inseries in the output circuit or by the opening contacts 29 controlled bythe winding 26. It will be observed that with this circuit arrangementthe starting or lighting up process is similar to that described withreference to Figure 2 but, owing to the contacts 29, it is impossible toclose the circuit breaking device 27 when the rectifying apparatus isnot suitably started on its shunt.

Moreover, in case of the failure of the supply of alternating current,the first effect of the re-establishment of the pressure is to actuatethe circuit breaking device 27, thus rendering impossible the startingof the apparatus on load.

In Figure 4 the rectifying apparatus is illustrated as being providedwith a maintaining circuit having special electrodes. A three-phasetransformer 30 is arranged to supply the main anodes 31 of the lamp, and

a separate transformer having double Winding 32 has its primary windingenergized for example from two of the supply terminals of thetransformer 30. The secondary winding of the transformer 32 is connectedat its extremities to the maintaining anodes 33 of the apparatus throughtwo induction coils 34 which maycooperate with the same magnetic circuitif desired, the neutral point of the secondary winding being connectedto the cathode 35 through an induction coil 36 controlling two pairs ofcontacts; an opening pair 37 and a closing pair 38.

The pair of contacts 37 areincluded in the starting or excitationcircuit comprising a winding 39 mounted on the maintaining transformer32 and a resistance 40.

On the other hand, included in the output circuit are a maximum relay 41and a contact device 42 provided with a closing auxiliary contact 43.The contact device 42 is provided with a controlling circuit comprisinga resistance 44 and two push buttons, one 45 for closing the other 46for opening.

The operation of the apparatus illustrated in Figure 4 is as follows Theprocess of starting or lighting is carried out as before by means of themaintaining circuit, and when the apparatus is suitably started, theWinding 36 opens the contacts 37, consequently insulating the startingelectrode device, and closes the contacts 38, thus permitting theclosing of the contact device and it is suflicient for this purpose topress the button 45. The closing coil attracts the armature, whichcloses the auxiliary contact 43 shunting the push button and insertingthe resistance 44 in the circuit. The circuit may be broken, either byactuating the push button 46, or, in case of too great acurrent, bfy theaction of the maximum relay 41. I the supply current fails, the contactdevice 42 opens, as is also the case when the maintaining circuit isaccidentally broken. In any event the apparatus cannot be started whilethe continuous current circuit is closed. y

In the case of two or more rectifying a paratus arranged in parallelwith their cat odes interconnected if it is desired to employ onecontact device only for protective purposes each rectifying apparatusmay be .provided with similar starting devices, but

it is then necessary to interpose in series in the closing circuit ofthe single contact device all the contacts corresponding to 38. All thelamps should be lighted up so that the contact device can be closed onthe external circuit.

It will be evident that the contact device can be operated by anautomatic device, on condition always, that such a device, only permitsthe contact device to close when all the maintaining circuits are inoperation.

It was supposed above that the closing winding of the contact device wasemployed in shunt with the continuous current circuit, but a closingwinding in series with the maintaining circuit, may be employed whichpermits the omission of the contacts 38, the latter arrangement beingrecommended in certain cases, in particular where a variable pressure isemployed.

An external casing device or internal grating device may still beemployed in the apparatus forpreventing starting under load it beingsufiicient to provide each projecting anode arm of the apparatus eitherwith an external or internal grating.

In order to prevent starting under load it is sufficient to employ asystem of relays similar to those described above in order to place thecasings or gratings at the same potential as the cathode so that themaintaining circuit is not energized and to the potential of thecorrespondinglanodes as soon as the maintaining circuit is energized.This arrangement is a plicable in particular to high tension recti ylngapparatus which always function at a low temperature, a circumstancefavoring the employment of casings and gratings.

The arrangements described above render impossible the closure of thecontinuous current circuit, when the starting of the rectifyingapparatus is not suitable. An arran-gement for permitting starting underload'i without permitting continuous current to traverse the startingelectrode may also be provided, it being sufficient for this purpose tointerpose in the startin circuit a condenser in series with a selfmductance in order to diminish its impedance.

Figure 5 illustrates such an arrangement. The autotransformer forsupplying current to the lamp 47 is provided with a starting winding 48connected to the starting electrode through a winding 50 and condenser49. It will be observed that in these conditions, the starting electrodewill be operated until continuous current is established in the cathodecircuit, inasmuch as it cannot be established in the lighting circuitbecause of the condenser. A relay (not illustrated in Figure 5) may beemployed for breaking the starting circuit and for placing the startingelectrode at the same potential as the cathode.

It will be evident that the invention is not limited to the particulararrangements hereinabove described which may be varied as required tosuit particular requirements.

Claims:

1. In va or rectifying apparatus, the combmation 0 an auxiliaryelectrode, bi-metallic means for actuating said electrode and meansincluding a tubular member for protecting said electrode and saidbi-metallic means from the action of the ionized vaporwithin theapparatus, said tubular member being mountedto permit deformation ofsaid bimetallic means.

2. In vapor rectifying apparatus, the combination 0 an auxiliaryelectrode, bi-metallic means for actuating said electrode and insulatingmeans including a tubular member surrounding said electrode and saidbi-metalhe means and protecting same from the ionized vapor within theapparatus, said tubular member bein mounted to permit deformation ofsaid bimetallic means.

3. In vapor rectifying apparatus, the combination of an auxiliaryelectrode composed of tungsten, bi-metallic means arranged to supportand actuate said electrode, an insulating casing surrounding saidbi-metallic means all mounted to permit deformation of said bi-metallicmeans and an insulating covering for a portion of said electrode.

4. In vapor rectifying apparatus, the combination of an auxiliaryelectrode made of tungsten, bi-metallic means 'for supporting andactuating said electrode, and insulating covering for said electrode andinsulating means surrounding said bi-metallic means.

In testimony whereof I affix my signature.

MAURICE AUGUSTE EUGENE LEBLANC.

